Implement detection of whether or not bounce-buffering is required

for the particular card in use.  At the moment, I've set it to any of
the bt445S VLB cards (not the bt445C which apparently work) and the
bt5xx series (isa cards).  The 742 and PCI cards should not need it. :-)

It may be useful to have something like this:
#ifndef BOUNCE_BUFFERS
  if (bounce_buffers_required && more_than_16MB_ram)
    panic("this card requires bounce buffers for more than 16MB ram!")
#endif

1 files changed, 10 insertions, 3 deletions

diff --git a/sys/i386/isa/bt742a.c b/sys/i386/isa/bt742a.c
index 8ab3c56..a092cea 100644
--- a/sys/i386/isa/bt742a.c
+++ b/sys/i386/isa/bt742a.c
@@ -12,7 +12,7 @@
  * on the understanding that TFS is not responsible for the correct
  * functioning of this software in any circumstances.
  *
- *      $Id: bt742a.c,v 1.43 1995/11/04 17:07:08 bde Exp $
+ *      $Id: bt742a.c,v 1.44 1995/12/06 23:50:06 bde Exp $
  */
 
 /*
@@ -382,6 +382,7 @@ struct bt_data {
 	int     bt_dma;			/* DMA channel read of board */
 	int     bt_scsi_dev;		/* adapters scsi id */
 	int     numccbs;		/* how many we have malloc'd */
+	int	bt_bounce;		/* should we bounce? */
 	struct scsi_link sc_link;	/* prototype for devs */
 }      *btdata[NBT];
 
@@ -702,7 +703,7 @@ btattach(dev)
 	bt->sc_link.adapter_targ = bt->bt_scsi_dev;
 	bt->sc_link.adapter = &bt_switch;
 	bt->sc_link.device = &bt_dev;
-	bt->sc_link.flags = SDEV_BOUNCE;
+	bt->sc_link.flags = bt->bt_bounce ? SDEV_BOUNCE : 0;
 
 	/*
 	 * Prepare the scsibus_data area for the upperlevel
@@ -1173,15 +1174,21 @@ bt_init(unit)
 			return (ENXIO);
 			break;
 	}
-	if ( binfo.id[0] == '5' ) {
+	if ( binfo.id[0] == '4' && binfo.id[1] == '4' && binfo.id[2] == '5' &&
+	     binfo.id[3] == 'S' ) {
+		printf("bt%d: Your card cannot DMA above 16MB boundary. Bounce buffering enabled.\n", unit);
+		bt->bt_bounce++;
+	} else if ( binfo.id[0] == '5' ) {
 		printf("bt%d: This driver is designed for using 32 bit addressing\n",unit);
 		printf("bt%d: mode firmware and EISA/PCI/VLB bus architectures\n",unit);
 		printf("bt%d: Bounce-buffering will be used (and is necessary)\n", unit);
 		printf("bt%d: if you have more than 16MBytes memory.\n",unit);
+		bt->bt_bounce++;
 	} else if ( info.bus_type == BT_BUS_TYPE_24bit ) {
 		printf("bt%d: Your board should report a 32bit bus architecture type..\n",unit);
 		printf("bt%d: The firmware on your board may have a problem with over\n",unit);
 		printf("bt%d: 16MBytes memory handling with this driver.\n",unit);
+		bt->bt_bounce++;
 	}
 
 	/*